FI108038B - Hydrophobic polymer dispersion and process for its preparation - Google Patents

Abstract

The invention relates to a hydrophobic polymer dispersion and a solvent-free process for the preparation thereof. According to the invention, the dispersion contains starch ester together with dispersion admixtures known as such. According to the process, the polymer is first mixed with a plasticizer in order to obtain a plasticized polymer blend. The plasticized polymer blend is then mixed with dispersion admixtures and water at an elevated temperature so as to form a dispersion. The plasticizing of the polymer and the dispersion of the mixture in water can be performed in an extruder. The obtained dispersion is homogenized in order to improve its stability. The dispersion obtained by the invention can be used to coat paper or board, as a primer or a component in paint or labeling adhesives, and it is also suitable for the production of cast films and as a binder in materials based on cellulose fibers, as well as for coating medicinal preparations.

Description

108038

Hydrophobic polymer dispersion and process for its preparation

The present invention relates to a hydrophobic polymer dispersion 5 according to the preamble of claim 1.

Such a dispersion contains modified starch dispersed in a liquid phase together with adjuvants known in the art for use in dispersions.

The invention also relates to a process for forming a hydrophobic polymer dispersion according to claim 15.

Emphasizing environmental friendliness and green values are creating new markets for products based on renewable resources. Such trends can be seen in 15 in the packaging, hygiene and adhesive industries, where recyclability, reuse, compostability, biodegradability and environmental friendliness are today's requirements. Emphasis is also placed on the tendency to substitute petrochemical products with biopolymer products. Starch and its derivatives provide a particularly interesting starting material for the preparation of biodegradable polymer products.

Polymer dispersions are used, for example, to coat paper and board to improve their water resistance. The dispersions currently used in the paper industry contain, in addition to fillers, various synthetic latexes which are relatively poorly degradable in the biological environment.

,. Solutions for the preparation of paper coating dispersions are known in the art

'*' Used modified starch components. Thus, WO application WO

93/11300 is known a hydrophobic coating composition based on a polymer dispersion containing a starch derivative grafted with a polymer containing styrene and butadiene monomers. Again, 2,108038 biodegradable components that are compatible with product recycling requirements are not used in this solution either.

It is an object of the present invention to provide a hydrophobic dispersion of which at least most, preferably substantially all of its components are biodegradable. In particular, it is an object of the invention to provide a dispersion whose polymer component consists essentially of a biodegradable polymer, preferably starch or a derivative thereof. It is a further object of the invention to provide a process for the preparation of hydrophobic dispersions.

10

The invention is based on the surprising discovery that many biodegradable polymers can advantageously be dispersed in water by first plasticizing and dispersing the plasticized molten in water with the aid of dispersants. No solvents are needed to prepare the dispersion. Thus, according to the present process, the 15 polymer is a biodegradable polymer, which is first blended with a plasticizer to produce a plasticized mixture, optionally mixed with excipients and water to form a dispersion, whereby mixing is performed at elevated temperature and 20 if desired homogenizing the resulting dispersion.

More specifically, the dispersion according to the invention is essentially characterized by what is stated in the characterizing part of claim 1.

The method according to the invention, in turn, is characterized by what is stated in the characterizing part of claim 15.

The invention provides considerable advantages. Thus, the raw materials of the starch dispersion of the invention disclosed are based largely on renewable resources and are biodegradable / compostable. The starch component may be derived from any natural starch; it need not be e.g. amylose rich starch. The formation of dispersion 3 108038 does not require the use of solvents which need to be evaporated off, but dispersion can be carried out on a melt-processing device, thereby substantially reducing the consumption of the plasticizer. The films formed from the dispersions are quite water repellent and can improve the water resistance of paper or board by at least 40 to 50 5%.

The new polymer dispersions can be used for coating paper or board, as a primer, as a label adhesive or as a paint component. They are also suitable for making hydrophobic casting films and as binders for cellulosic fiber based materials.

10

The present invention will now be explored in greater detail by means of a detailed description and embodiments.

As shown, hydrophobic starch dispersions containing starch starch, starch starch, starch starch, starch starch, starch starch, hydrolysed starch, oxidized starch, cross-linked starch or gelatinized starch starch, Hydrophobic polymer dispersions of other biodegradable polymers such as polycaprolactone, lactic acid polymers, polylactide 20 and / or polyhydroxybutyrate / valerate may also be prepared. Of course, the latter polymers can be used in admixture with starch polymers. Particularly preferred are hydrophobic starch ester-containing polymer dispersions.

In the composition of the invention, starch or a derivative thereof, hereinafter also referred to as the starch component, may be based on any natural starch having an amylose content of 0 to 100% and an amylopectin content of 100 to 0%. Thus, the starch component may be derived from barley, potatoes, wheat, oats, peas, corn, tapioca, sago, rice, or the like. It may also be based on starches prepared from said natural starches by oxidation, hydrolysis, crosslinking, cationization, grafting, etherification or esterification.

4, 108038

It has been found advantageous to use a starch based component derived from an ester of starch and one or more C2.24 aliphatic carboxylic acids. The carboxylic acid component of such an ester may then be derived from a lower alkanoic acid such as acetic acid, propionic acid or butyric acid, or a mixture thereof. However, the carboxylic acid component may also be derived from naturally occurring saturated or unsaturated fatty acids. Examples of these include palmitic acid, stearic acid, oleic acid, linoleic acid and mixtures thereof. The ester may also be composed of both long and short chain carboxylic acid components. An example is a mixed ester of acetate and stearate.

The fatty acid esters of starch are prepared, e.g., as disclosed in Wolff, I.A., Olds, D.W. and Hilbert, G.E., The Acylation of Com Starch, Amylose and Amylopectin, J. Amer. Chem. Soc. 73, 346-349 (1952) or Gros, A.T. and Feuge, R.O., Properties of Fatty Acid Esters of Amylose, J. Amer. Oil Chemists' Soc 15 39 (1962) 19-24.

Starch acetates can be prepared by reacting the starch with acetic anhydride in the presence of a catalyst. For example, 50% sodium hydroxide is used as the catalyst. Other known acetate preparation methods disclosed in the literature are suitable for the preparation of starch acetate. By varying the amount of acetic anhydride, the amount of the base used as the catalyst and the reaction time, starch acetates of varying degrees of substitution can be prepared.

Preferably, the starch component is an esterified starch, most preferably starch acetate, having a degree of substitution of 0.5-3, preferably 1.5-3, and preferably 2-3. Particularly preferred are starch esters, e.g., enzymatically hydrolyzed barley starch.

As mentioned above, the starch component is plasticized by admixing it with a plasticizer known as such. The dispersion composition according to the invention therefore preferably contains from 0.01 to 95% by weight, preferably from about 1 to 5 108038% by weight of a plasticizer. Any of the known plasticizers suitable for use include, for example, the following: triacetin, diacetine, monoacetine, triethyl citrate, tributyl citrate, acetyl triethyl citrate, acetyl tributyl citrate, dimethyl succinate, diethyl succinate, ethyl acyl lactate, , diethyl talcate, and mixtures thereof.

The starch dispersion further contains a dispersion adjuvant to disperse the plasticized polymer melt in finely divided particles in water to form a stable dispersion. Examples of dispersion auxiliaries include polyvinyl alcohol (PVA), particularly PVA having a weight-based molecular weight of about 10,000 to 115,000. Other dispersion aids (protective colloids) include cationic starch and hydroxyalkyl starch, which may be used alone or in combination with PVA. The dispersions may further contain alkyl ketene dimer (AKD) wax and beeswax as additives or excipients.

As an example of preferred polymer dispersion compositions may be mentioned a composition comprising 5 to 25 parts by weight of starch ester, 20 to 50 parts by weight of plasticizer, 1 to 150 parts by weight of water and 1 to 20 parts by weight of a dispersion adjuvant.

Typically, the amount of water is about 2 to about 10, preferably about 4 to about 6, the amount of plasticizer is about 0.1 to about 2, and the amount of excipient is about 0.1 to about 1, 5-fold biodegradation -; *. * Compared to the amount of polymer. Thus, as an example of the preparation of a hydrophobic starch ester dispersion, it can be mentioned that about 1.0 to 5 kg of starch ester, 0.5 to 6 kg of plasticizer and about 0.1 to 1.5 kg of excipient can be dispersed in 10 kg of water.

Such a polymer dispersion may further comprise from 0.01% by weight to 30% by weight, preferably from about 5% to about 30% by weight, of a cellulose ester such as cellulose acetate, propionate or butyrate, or mixed esters thereof.

The present dispersion compositions are prepared by dispersing the plasticized polymer in water with the aid of excipients. To effect plasticization, the biodegradable polymer is blended with the plasticizer, preferably at elevated temperature, to form a molten material. On a small scale, plasticization can be carried out, for example, with a reflux condenser in a flask equipped with efficient mixing. The temperature will vary depending on the plasticizer used but is typically about 50-250 ° C, preferably about 100-200 ° C. On a larger scale, it is preferable to perform the plasticization in a melt-10 machining device such as an extruder.

The plasticized melt is dispersed in the liquid phase, usually water, with the aid of excipients. Water is considered a particularly preferred dispersion medium of the invention, but the invention can also be applied to a variety of solvents.

15

The excipient and water may be added in optional stiffening. Thus, the excipient may first be added to the plasticized polymer melt and then the water or excipient may be dissolved in water and added with the water. In both cases, it is preferable to gradually add water. Preferably, the addition of water and excipient is carried out at such a rate that the plastified mass 20 remains uniform and no phase separation occurs. According to a preferred embodiment, this can be accomplished by pumping the water with a drop of water or otherwise in small amounts into a hot plasticized biopolymer, e.g., a starch derivative or starch. During the addition, the evaporated water is condensed and returned to the mixture. In the preparation of starch-based dispersions, it is particularly advantageous to initially add a small amount of water dropwise to the molten mass and suspend the addition for a period of time, typically 5 to 30 minutes, to ensure that the mass is well mixed and uniform. The water is then added dropwise until all the water is added. For other biodegradable polymers, water may be added without interrupting addition.

30 '· According to a particularly preferred embodiment, the dispersion is prepared by mixing 5 to 25 parts by weight of starch ester with 5 to 50 parts by weight of plasticizer to form a plasticized starch ester mixture, the liquid phase being maintained at a temperature of about 100-180 ° C. and adding from 1 to 150 parts by weight of water and from 1 to 20 parts by weight of a dispersion adjuvant to the plasticized starch ester mixture, maintaining the liquid phase at a temperature of about 50 to 100 ° C during the addition of water.

According to another particularly preferred embodiment, the preparation is carried out by mixing 10 5 to 25 parts by weight of a starch ester, 5 to 50 parts by weight of a plasticizer and 1 to 20 parts by weight of an adjuvant in a plasticized starch blend at 100-250 ° C. -150 parts by weight of water at a temperature of about 50-1500 ° C to form a hydrophobic dispersion.

However, the dispersion can also be accomplished by mixing the excipient with water and merely mixing the starch ester and plasticizer in a melt processing machine.

After dispersion, the dispersion, if desired, is homogenized in a manner known per se to stabilize it. For example, homogenization can be achieved by a pressure homogenizer. As shown in Example 2, homogenization can reduce the particle size by 50-100% and thus improve dispersion stability. The dispersions of the invention are stable for several weeks, even months.

25 Γ. The invention provides dispersions of biodegradable polymers, particularly starch derivatives, particularly preferably starch esters, wherein 90% of the particles of the polymer are smaller than 10 µπι. Homogenization gives dispersions with average particle sizes less than 2 μπι or even less than 1 μπι. Depending on the application, dispersions having a multimodal, essentially bimodal - '* sleep particle size distribution can be further prepared.

8 108038

The following non-limiting examples illustrate the invention. The degree of substitution of starch acetates reported in the examples is determined according to Wurzburg (Wurzburg, O.B, Acetylation, Methods in Carbohydrate Chemistry, Vol. IV, R.L. Whistler, Academic Press, New York and London, 1964, p. 288).

5

Example 1

Enzymatically Hydrolyzed Starch 10 Enzymatically hydrolyzed starch suitable for the preparation of starch esters is obtained by the addition of thermo-α-amylase to the aqueous starch slurry, after which the slurry is passed through a jet digester, whereupon steam is added. The enzyme is allowed to act until the starch is sufficiently cleaved. The process is monitored by measuring the viscosity of the slurry. When the viscosity is desired, the enzyme is inactivated and the starch is dried.

Example 2 Starch acetate dispersion 20.0 g of starch acetate made from enzymatically hydrolyzed barley starch prepared according to the method of WO 95/33450 having a DS of 2.8 and 87.5 g of triacetin (Unichema: Priacetin) are refluxed effectively stirring with a knife blender until the mixture is homogeneous and translucent. The temperature of the mixture is then about 160 ° C. To the molten is added 16.3 g of polyvinyl alcohol (Hoechst, molecular weight 20,000 and degree of hydrolysis 74%) and * is stirred for 10 min, after which 12 ml of water are slowly added at about 90 ° C. Stir an additional 15 min and slowly add 213 g of hot (ca. 90 ° C) water while stirring. The temperature is maintained at about 95 ° C. After the water has been added, stirring is continued for another 15 minutes, after which the mixture is cooled in a water bath to room temperature. The resulting homogeneous dispersion has a viscosity, measured at Bohlin viscosity, for example, of '·: 2.92E + 2 1 / s of 2.05E-1 Pas and an average particle size of 2.7 µm and 90% of the particles. as measured by a laser diffraction particle size analyzer.

When it is desired to further reduce the particle size, the solution can be homogenized by a pressure homogenizer, whereby at 1000 bar the average particle size 5 drops to 2.0 µm and 90% of the particles are less than 4.8%. If the treatment is repeated, the average particle size will be about 1.5 µm and then 90% of the particles will be less than 3.6 µm.

The dispersion remains stable at room temperature for several weeks. By varying the amount of water added, the viscosity of the solution can be controlled.

Example 3 Starch acetate dispersion containing AKD wax 50.0 g starch acetate starch prepared from enzymatically hydrolyzed barley starch having 2.8, 77.5 g triacetin (Unichema: Priacetin) and 10.0 g alkyl ketene dimer wax (Raisio Chemicals: melt in a reflux flask with an electric bath, stirring vigorously under stirring, until the mixture is homogeneous and translucent. 12 ml of hot (90 ° C) water is added slowly, followed by addition of 16.3 g of polyvinyl alcohol (Hoechst, molecular weight 20,000 and degree of hydrolysis 74%) and stirring for 10 min. Then, 208 g of hot water is added with vigorous stirring (400 rpm). The temperature of the mixture is maintained at 90-95 ° C. Cool in a water bath to about 30 ° C with vigorous stirring. The viscosity of the homogeneous dispersion as measured by a Bohlin viscometer at 2.92E + 21 / s is 6.29E-1 Pas.

25; * Example 4 * Starch acetate dispersion containing hydroxypropyl starch as an excipient

According to Example 2, 50.0 g of starch acetate having a DS of 2.8 are softened with 87.5 g of 30 triacetin. Dissolve 16.3 g of hydroxypropyl starch (Primalco, COHPOL LL 100), *: MS in 0.4,220 g of water. Add 12 ml of hot hydroxypropyl starch solution 108038 to a homogeneous melt and stir for 15 min, then slowly add the remaining hydroxypropyl starch solution with vigorous stirring while maintaining the temperature of the mixture at about 90 ° C. The result is a homogeneous stable dispersion in which the hydroxypropyl starch serves as a protective colloid and no phase separation is observed. 5

Example 5 Starch acetate dispersion in which 50.0 g of starch acetate cationic starch acetate (2.8) DS and 87.5 g of triacetin (Unichema: Priacetin) are melted as described in Example 2. Dissolve 4.0 g of cationized starch (Raisio Chemicals: Raisamyl 150) in 220 g of warm water. Add 12 ml of hot starch solution to a homogeneous melt and stir for 15 min, then slowly add the rest of the starch solution with vigorous stirring, keeping the temperature of the mixture at about 90 ° C. A homogeneous milky dispersion having a viscosity measured with a Bohlin viscometer, e.g., at 2.92E + 21 / s is 6.06E-1 Pas is obtained.

When the resulting dispersion is coated by cardboard on a board having a Cobb60 value of 24.5 g / m 2 for the Cobb60 test for water adsorption capability, the film thickness is 24.2 g / m 2 coated. '. the Cobb60 value of the board is 17.2 g / m2, which means that the coating can improve the water resistance of the board by 30%.

Example 6 25 Starch acetate dispersion with dimethyl succinate and AKD wax 50.0 g of enzymatically hydrolyzed barley starch starch acetate having a DS of 2.8, 87.5 g of dimethyl succinate (Fluka) are refluxed with th at a temperature until the mixture is homogeneous and translucent. Add 20.0 g of alkyl ketene dimer wax (Raisio Chemicals: Raisares A) to the melt, keep the temperature of the mixture 11 108038 at 115 ° C and stir for 5 min. Add 16.3 g of polyvinyl alcohol (Hoechst, molecular weight 20,000 and degree of hydrolysis 74%) and stir for 10 min. Gradually add 12 ml of hot water with stirring, stir for 15 min and add 208 g of hot water. The resulting dispersion is homogeneous and has a viscosity measured with a Bohlin-5 viscometer e.g. at 2.92E + 21 / s at 7.57E-1 Pas. When the resulting dispersion is coated with board coating on a board having a Cobb60 value of 23.5 g / m 2, the film thickness of 18.0 g / m 2 on the coated board is 8.8 g / m 2, which improves water resistance by 62%.

Example 7

Dispersion of known biopolymers

Commercial biopolymers, polyhydroxybuturate / valerate and, on the other hand, poly-ε-caprolactone were dispersed by the method described in Example 2.

15

The compositions of the dispersions are shown in the table below.

Table 1. Compositions of Dispersions of Biopolymers 20 ___ * ·; Substance 12 3 PHB / PHV a) 50, Og

Poly-B-caprolactone b) 50, Og PLLAc) 50, Og 25 Polyvinyl alcohol d) 16.0g 16.0g 16.0g water 200g 200g 200g

(a) Zeneca, Biopol D 310G

b) Union Carbide, Tone 767 30 c) Neste Chemicals d) Hoechst, molecular weight 20,000, degree of hydrolysis 74% 12 108038

Using polyhydroxybuturate / valerate, a granular dispersion was obtained which after 7d was clearly fractionated.

Poly-s-caprolactone gave a visually homogeneous, stable dispersion which, after 5 weeks of storage, was divided into different phases.

PLLA gave a homogeneous dispersion which remained stable below 3d.

Example 8 10 Starch palmitate dispersions

The acid hydrolyzed starch was prepared as described in WO 95/33450. Starch palmitates were prepared by the process of patent application FI954742.

Melt starch palmitate and dibutyl phthalate in a flask at 60-95 ° C depending on the melting point of palmitate. Water or buffer solution is added to the molten mass at a temperature of 50-60 "Cm. The polyvinyl alcohol is dissolved in water or buffer solution. The water / polyvinyl alcohol addition is done in stages by first adding about 10% of the total and mixing with 20 clubs for 15 min. water gradually and stirring for 20 min keeping the temperature of the mixture at 60-95 ° C. The mixture is then allowed to cool to room temperature for about 30 min.

The compositions of the dispersions are shown in the following table in weight percentages.

13108038

Table 2. Starch palmitate dispersions

Substance__1__2__3__4___5__6 Starch DS2.8 DS 0.7 DS2.7 DS0.7 DS2.8 DS2.7 Palmitate Starting Starch Starting Starch Starting Starch Starting Starch Starting Starch Native Kelly Native Kelly Acid Kelly Hydrolyzed Barley Hydrolyzed acid a) b) hydro- 17.5 16 19.3 18.2 15.4 lysed) ______ 19.3

Dibutyl phthalate 17.5_16_19J_lftf_ 15.4 14.5

Polyvinyl 3,9 4 3,4 4,2 3,5 3,4 alcohol c) _______

Surfactant 4.8

Span 20_______

Water 61.1_64_58 ^ 0__59 ^ __ 58.0

Buffer solution 65.6

pH 7 ___1 I

a) Hydrolysis time 3 h, b) Hydrolysis time 0.5 h 5 c) Polyvinyl alcohol (BDH, Molecular weight 115,000, 87% hydrolysis)

The dispersions were stored for several weeks at room temperature. No phase separation occurred ... ie the dispersions remained stable.

Example 9

Water Permeability of Dispersion Films by Diffusion Chamber Testing

From the starch acetate dispersions 2 and 4 described in Example 8, films were made on a Teflonized glass surface using a film applicator. The films were dried at room temperature and detached from the glass plate.

The water permeability of a film having a mean thickness of 0.1 mm was examined by diffusion chamber tests where the film is placed between two chambers and the penetration of tritium through the membrane is measured in 40 mM phosphate buffer, pH 7. The diffused tritium is measured as a function of time.

5% of Tritium was penetrated through the membrane prepared from Dispersion 2 and about 6% for Dispersion 4. After three hours, the values were 10% and 18%, respectively.

The corresponding dispersion was prepared from acid hydrolyzed starch acetate having a DS of 2.5. The dispersion composition, by weight, was 16.1% 10% acetate, 24.1% dibutylphthalate, 3.6% polyvinyl alcohol and 56.2% water.

• Preparation was carried out as described in Example 7. This dispersion was made into a film in the same manner as the palmitate dispersions and similarly tested by diffusion tests. Penetrated amounts of tritium were 17% / 0.5 h, 20% / 1 h and 23% / 3 h.

15 Although the penetration results can only be considered indicative due to the water evaporation pores present in the membranes, which were visible in the SEM images (all membranes have the same number of pores and the same level), the results suggest that penetration is slower than the the corresponding 20 palmitates of starch. Penetration is clearly accelerated when the ester chain length is shorter, even though the degree of substitution is higher.

Example 10 Moisture Permeability of a Film Made from Starch Acetate Dispersion A starch acetate dispersion was prepared according to the method described in Example 2. The composition of the dispersion, expressed as weight percent, was 13% starch acetate (DS 2.8) made from enzymatically hydrolyzed starch, 23% triacetin, 4.3% polyvinyl alcohol (molecular weight 115,000, degree of hydrolysis 87%) and water 59.4%. The membranes 30 were cast as described in Example 9. The experiment measured the moisture permeability of the membranes at various moisture contents by parallel determinations.

15 108038

Calcium chloride used as a desiccant was weighed into the vial. A dispersion molded film was placed on the bottle mouth and the bottle was carefully closed so that each bottle had an equal film surface for moisture permeability measurement. The flasks were placed in different desiccators with relative humidity and the weight of desiccant 5 increased over time, indicating the amount of moisture passing through the membrane. The results are shown in the following table.

Table 3. Permeability of Dispersion Films 10 Time Relative Humidity Relative Humidity Relative Humidity Daily 33% 60% 80% 3 0.6% T% ~ ~ 1.5% 5_ 1.2% _ 1.5% _2.5% _ 10_2.0% _3.2% _4.2% _ 15 20_4.0% _5.5% _8.0% _ 22_6.2% _ 8.0% _ 10% _

The results show that the moisture permeability of the films cast from the dispersions remains quite low even for a long period of time. Due to the manufacturing method, 20 pores were present in the membranes, suggesting that the values are lower if the porosity is not ^ ·. occur.

Example 11

Effect of Polyvinyl Alcohol Amount on Dispersion Particle Size 25 · * The dispersion formulation described in Example 10 changed the amount of polyvinyl alcohol by 3.7% w / w and 4.9% w / w and examined the particle size of the dispersions using a light microscope and light scattering particle size determination apparatus (Nicomp®). With the smallest amount of polyvinyl alcohol, the largest particles were 25-40 µm and the smallest 7-13 µm based on light microscopic measurements. The particle size of this dispersion was so large that it was out of range of the Nicomp instrument.

16 108038

As the amount of polyvinyl alcohol rose to 4.3%, the largest particles were of the order of 20 µm, the average 10 µm, and the small particles 1.5 to 3.4 µm by Nicomp measurement. As the amount of polyvinyl alcohol was further increased, the size of the largest particles was reduced to 13-16 µm and medium size 7 µm. However, the majority of the 5 particles were small. Their size was obtained by light scattering measurement of 0.3-0.6 µm and 2.9-6.5 µm.

In summary, the results indicate that increasing the amount of polyvinyl alcohol reduces the particle size of the dispersion.

10

Example 12

Effect of different plasticizers on particle size of starch acetate dispersion

The formulation of the dispersion described in Example 11 was modified so that half of the triacetin was replaced by triethyl citrate. The particle size of the dispersions was measured as described in Example 11.

In the triethyl citrate dispersion, the size of the largest particles was reduced by half under light microscopy, and the small particles obtained sizes from 0.1 to 0.2 µm (97.5%) and 1.1 to 2.5 µm (2.5%) in Nicomp-20 measurements.

The particle size of the dispersion in which all the triacetin is replaced by triethyl citrate is of the same order of magnitude as that of a mixture of both plasticizers.

25 Example 13 *, Storage stability of dispersions

Dispersion formulations according to the following table were prepared. The amounts of substances are expressed as weight percentages.

30 17 108038

Table 4. Storage stability of dispersions

Ingredients Composition 1 Composition 2 Composition 3 5 Starch acetate PS 2.8 a) _ 13.1% __ 14.2% __ 13.6%

Triacetin_22.9% __-__ 11.9% _

Triethyl Citrate__16.0% __ 8.5% _

Polyvinyl Alcohol 4.2% _ 5.0% _4.4% _ 10 Water 58.8% 64.1% 61.0%

Antifoam agent b) 1.0% _0.7% _0.6% _ a) Starch acetate made from enzymatically hydrolyzed barley starch b) Wacker Silicone AS-EM.SLE 15

The dispersions were stored at room temperature in closed stacks for two months, during which they measured viscosity stability and particle size change during storage and monitored for phase separation.

The viscosities of the dispersions were measured as a function of time with the Haake Viscotester VT-02 (Ser.no. 83722). The following table shows the measured viscosities: m m

Table 5. Viscosities of Dispersion 25 Viscosities, Poise

Dispersion Ovrk 10 days 20 days 30 days 40 days

Composition 1 15__15__H__12.5__12

Composition 2 _20__19__1_8__18__19

Compositions 3 18 18 18 18 18.5

There were no significant changes in the viscosities of the dispersions during storage, indicating good stability.

30 18 108038

Particle sizes of the triacetin-based dispersion (Composition 1) were measured immediately after preparation and 1 and 2 months after preparation. The measurement was performed with both light microscopy and light scattering measurement (Nicomp). There were no changes in the size of the small particles in the Nicomp measurements within two months. Under the light-5 microscope, the size of large particles was slightly increased during storage.

No visual phase separation was observed in the dispersions during storage.

Example 14 Preparation of a Starch Acetate Succinate Based Dispersion

Preparation was carried out in the same manner as starch acetate dispersions. The formulation was as follows: 13.7% w / w Starch acetate succinate (DSAcet 1.34 and DSSuc 0.25), 23.9% triacetin, 4.4% polyvinyl alcohol and 58.0% water. Starch acetate-15 succinate was prepared as disclosed in US 08/498341. There was no phase separation in the dispersion during storage.

Example 15

Use of dispersions in label adhesives 20

The dispersions were prepared using adhesive formulations using tall oil resin based adhesive resin dispersions as the adhesive resin components. The dispersion was applied to the glazing with an applicator stick. The adhesive was inoculated from a glass plate to a roll of label paper (50 x 120 mm). The label strip was then glued onto a second sheet of glass by rolling so that 25 air bubbles did not remain on the adhesive surface. The label was glued on a glass plate so that the adhesive area was 5x ·. 100mm. The glued labels were aerated for 24 hours (34 ° C, RH 50%). The wash time was determined from the adhesives by placing a 20 g weight on the label portion outside the adhesive surface and placing the glass plate with its weights in a cold water basin with constant cold water circulation. At the time of insertion, the chronographs were started to measure the 30 time it took to remove the label from the glass plate. The test indicates the stability of the bottle labels in humid conditions.

19 1 08038 'Table 6. Washability of label adhesives!

Experience Dispersion Adhesive Resin Adhesive Resin Adhesive Resin

Example Oulutac 30 D Snowtack Snowtack 377F Time ___301A___ l_ 150 g 150g ___> lOh_ 5 2 150 g 32 g 2 h 30 min 3 150 g 18 g 42 min 4 150 g 21.5 g 2h5min 5 150 g 21.5 g 1 h 50 min

Dispersion 10 Example 1__50 min_

Commercial label adhesive__2 h lOmin_

Oulutac 30 D; Manufacturer Forchem Oy 15 Snowtack 301 Aja377F, ManufacturerAkzoNobel

Example 16

Use of Dispersion in Extrusion Coating as Priming Material The dispersion of Example 2 was used in board and paper extrusion coating by first making a dispersion coated board with a hand applicator. Subsequently, a dispersion-coated board (the so-called lower web) was run on a Brabender Plasti-Corder® flat film nozzle (geometry 20 * 0.8 * 100, 0.5 mm lip spacing), which was cooled between a press or nip roll and a coil 25 on the surface of the carton coated with dispersions.

The purpose of the primers is to improve the adhesion of the extrusion coating materials to the paperboard or paper, i.e. the adhesion between the coating and the paperboard.

The adhesion between the coating and the board was determined by a so-called. As a T-Peel test according to ASTM standard

20 108038

D8787-72. In the method, the anti-gravity apparatus determined the force required to remove the coating from the surface of the paperboard.

The primer property of the dispersion was tested by comparing the adhesion of the materials described in P.Salmi's thesis [1] with a primer and a non-primer lower track.

Material T-Peel Value [N / m] 10 Non-Primerized Cardboard Dispersion-primed cardboard C6L50-CT 9-26 p (> 120) 15 p = the cardboard was exposed, causing the cardboard to tear while retaining the coating when pulled. The adhesion was perfect.

20 [1] Salmi p., Biomass of starch in extrusion coating, Master's thesis. 1995

Tampere University of Technology, Tampere, 156 p.

*

Example 17 Biodegradability of starch acetate dispersion 25

The dispersion prepared according to Example 2 was studied for biodegradability *. A test based on the determination of carbon dioxide formed, whereby the sample was incubated at + 25 - 30 ° C in an inoculum of purified sewage sludge from an activated sludge plant. The carbon dioxide formed is absorbed into the KOH solution to form potassium carbonate, which is further analyzed for carbon dioxide. Calculating the biodegradability according to the following formula: Biodegradability (%) = (measured as CO 2 / theoretically released from the sample) 1100, the result is that the sample already decays 65% at 6d and 73% at 21d * 21 108038. It is generally considered that at a test yield of 60 to 70% of theory, the sample is biodegradable.

Example 18 5 Disintegration of dispersion coated board in compost

The disintegration of the carton coated with the dispersion prepared according to Example 2 was investigated by a composting environmental test with real composting conditions, natural aeration and monitoring of activity parameters (temperature, humidity, CO 2.02, C / N-10 ratio). The test was carried out at the VTT (State Technical Research Center) Bio and Food Technology Research Unit. The test equipment consisted of composters connected to an automatic CO2 and temperature measuring apparatus. The compost was filled and maintained according to a well-planned plan. The degradation of the test samples was visually inspected weekly during bio-waste inversion. Visually, the sample disintegrated at approximately 80% within 70 to 15 days and 90% according to the weight loss result. 1 «<r (

Claims (29)

22 108038 A hydrophobic polymer dispersion containing modified starch dispersed in water together with adjuvants known in the art for use in dispersions, characterized in that: - the modified starch consists of a starch ester made from natural starch and has a degree of substitution (DS) of greater than 1.5; the dispersion also contains a starch ester plasticizer. Polymer dispersion according to Claim 1, characterized in that the starch ester is derived from an ester of starch and one or more C2-24 aliphatic carboxylic acids. Polymer dispersion according to claim 2, characterized in that the carboxylic acid component of the ester 15 is derived from acetic acid, propionic acid or butyric acid or a mixture thereof. Polymer dispersion according to Claim 2, characterized in that the carboxylic acid component is derived from naturally occurring saturated or unsaturated fatty acids. Polymer dispersion according to claim 4, characterized in that the carboxylic acid component is derived from palmitic acid, stearic acid, oleic acid, linoleic acid or a mixture thereof. 25 Polymer dispersion according to one of claims 2 to 5, characterized in that. the starch ester contains both long and short chain carboxylic acid components. Polymer dispersion according to claim 6, characterized in that the starch ester is a mixed ester of starch and acetic acid and stearic acid. Polymer dispersion according to one of the preceding claims, characterized in that the degree of substitution (DS) of the starch ester is 2.0 to 3.0. 23 108038 Polymer dispersion according to one of the preceding claims, characterized in that the starch feedstock has an amylose content of 0-100% and an amylopectin content of 100-0%. Polymer dispersion according to one of claims 1 to 9, characterized in that it contains polyvinyl alcohol, cationic starch and / or hydroxyalkyl starch as an excipient in the dispersion. The polymer dispersion according to any one of claims 1 to 10, characterized in that it contains an alkyl ketene dimer (AKD) wax or beeswax as an additive to the dispersion. 12. A polymer dispersion according to claim 1, characterized in that it contains as a plasticizer triacetin, diacetine, monoacetine, triethyl citrate, tri-butyl citrate, acetyl triethyl citrate, acetyl tributyl citrate, dimethyl succinate, dimethyl succinate, rapeseed oil, tall oil, dibutyl phthalate, diethyl phthalate, or a mixture thereof. Polymer dispersion according to Claim 1, characterized in that it contains 5 to 25 parts by weight of starch ester, 5 to 50 parts by weight of plasticizer, ≤ 1 to 150 parts by weight of water and 1 to 20 parts by weight of a dispersion adjuvant. 25 Polymer dispersion according to one of the preceding claims, characterized in that it further contains from 0.01 to 30% by weight, preferably from 5 to 30% by weight, of a cellulose ester such as cellulose acetate, propionate or butyrate or a mixed ester thereof. . 15. A method of forming a hydrophobic polymer dispersion which comprises using a biodegradable polymer dispersed in water with aids known per se, characterized in that the polymer is first blended with a plasticizer at an elevated temperature to produce a plasticized polymer blend, a plasticized polymer blend. excipients and water to form a dispersion, wherein the mixing is carried out at elevated temperature and, if desired, homogenizing said dispersion. Method according to Claim 15, characterized in that the polymer 10 is mixed with the plasticizer in a melt-processing machine. Process according to Claim 15 or 16, characterized in that the starch ester, starch ester, or starch ester made from natural starch, hydrolyzed starch, oxidized starch, crosslinked starch, gelatinized starch, starch ester, or polyhydroxy butyrate / valerate. Process according to any one of claims 15 to 17, characterized in that the plasticizer used is triacetin, diacetine, monoacetine, triethyl citrate, tributyl citrate, acetyl triethyl citrate, acetyl tributyl citrate, dimethyl succinate, diethyl succinate, rapeseed oil, tall oil, dibutyl phthalate, diethyl phthalate or a mixture thereof. Process according to one of Claims 15 to 18, characterized in that polyvinyl alcohol, cationic starch and / or hydroxyalkyl starch are used as an excipient. Process according to claim 19, characterized in that the polyvinyl alcohol has a weight-based molecular weight of about 10,000 to 115,000. Method according to one of Claims 15 to 20, characterized in that | The 108038 dispersion additive used is an alkyl ketene dimer (AKD) wax or beeswax. Process according to any one of claims 15 to 21, characterized in that 5 to 25 parts by weight of starch ester are mixed with 5 to 50 parts by weight of plasticizers to form a plasticized starch ester mixture, the liquid phase being maintained at a temperature of about 100-180 ° C and 1 to 150 parts by weight of water and 1 to 20 parts by weight of a dispersion adjuvant are added, during which the liquid phase is maintained at a temperature of about 50 to 100 ° C. 10 Process according to Claim 22, characterized in that an adjuvant and then water are added to the plasticized starch. Process according to claim 22, characterized in that the excipient is first dissolved in water, which is then added to the plasticized starch. Process according to one of Claims 22 to 24, characterized in that the water and the excipient are gradually added to the plasticized starch. Process according to Claim 25, characterized in that the water and the excipient are added with a kneading stick such that the plasticized mass remains uniform and there is no phase separation. * Process according to one of Claims 15 to 22, characterized in that 25 to 5 to 25 parts by weight of starch ester, 5 to 50 parts by weight of plasticizer and 1 to 20 parts by weight of adjuvant are mixed together in a polymer melting machine at 100 to 250 ° C. temperature to form a plasticized starch ester mixture; and the 30 '- plasticized starch ester mixture is mixed with 1 to 150 parts by weight of water at about 50 to 100 ° C to form a hydrophobic dispersion. Use of a polymer dispersion according to any one of claims 1 to 14 or one of claims 15 to 27 for coating paper or board, as a primer, as a label adhesive or as a paint component. Use of a polymer dispersion prepared by the process of any one of claims 1 to 14 or one of claims 15 to 27 for the production of cast films and as a binder for cellulosic fiber based materials. * t · m 27 1 08038 I Patentkrav: